src/test/ui/issues/issue-10401.stderr

   1 error[E0368]: binary assignment operation `+=` cannot be applied to type `&str`
   2   --> $DIR/issue-10401.rs:3:5
   3    |
   4 LL |     a += { "b" };
   5    |     -^^^^^^^^^^^
   6    |     |
   7    |     cannot use `+=` on type `&str`
   8
   9 error: aborting due to previous error
  10
  11 For more information about this error, try `rustc --explain E0368`.